296 lines
7.3 KiB
C
296 lines
7.3 KiB
C
/*
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* GL_EXT_texture_lod_bias demo
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*
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* Thanks to Michael Vance for implementing this extension in Mesa.
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*
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* Brian Paul
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* 20 March 2000
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*
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* Copyright (C) 2000 Brian Paul All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <assert.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#include <GL/glut.h>
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#include <GL/glext.h>
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#include "readtex.h"
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#define TEXTURE_FILE "../images/girl.rgb"
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static GLfloat Xrot = 0, Yrot = -30, Zrot = 0;
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static GLboolean Anim = GL_TRUE;
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static GLint Bias = 0, BiasStepSign = +1; /* ints avoid fp precision problem */
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static GLint BiasMin = -400, BiasMax = 400;
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static int win = 0;
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static void
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PrintString(const char *s)
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{
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while (*s) {
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glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
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s++;
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}
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}
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static void Idle( void )
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{
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static int lastTime = 0;
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int time = glutGet(GLUT_ELAPSED_TIME);
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int step;
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if (lastTime == 0)
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lastTime = time;
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else if (time - lastTime < 10)
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return;
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step = (time - lastTime) / 10 * BiasStepSign;
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lastTime = time;
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Bias += step;
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if (Bias < BiasMin) {
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Bias = BiasMin;
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BiasStepSign = +1;
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}
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else if (Bias > BiasMax) {
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Bias = BiasMax;
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BiasStepSign = -1;
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}
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glutPostRedisplay();
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}
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static void Display( void )
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{
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char str[100];
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glClear( GL_COLOR_BUFFER_BIT );
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glMatrixMode( GL_PROJECTION );
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glLoadIdentity();
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glOrtho(-1, 1, -1, 1, -1, 1);
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glMatrixMode( GL_MODELVIEW );
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glLoadIdentity();
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glDisable(GL_TEXTURE_2D);
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glColor3f(1,1,1);
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glRasterPos3f(-0.9, -0.9, 0.0);
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sprintf(str, "Texture LOD Bias = %4.1f", Bias * 0.01);
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PrintString(str);
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glMatrixMode( GL_PROJECTION );
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glLoadIdentity();
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glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
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glMatrixMode( GL_MODELVIEW );
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glLoadIdentity();
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glTranslatef( 0.0, 0.0, -8.0 );
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glPushMatrix();
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glRotatef(Xrot, 1, 0, 0);
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glRotatef(Yrot, 0, 1, 0);
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glRotatef(Zrot, 0, 0, 1);
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glEnable(GL_TEXTURE_2D);
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glTexEnvf(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, 0.01 * Bias);
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glBegin(GL_POLYGON);
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glTexCoord2f(0, 0); glVertex2f(-1, -1);
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glTexCoord2f(2, 0); glVertex2f( 1, -1);
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glTexCoord2f(2, 2); glVertex2f( 1, 1);
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glTexCoord2f(0, 2); glVertex2f(-1, 1);
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glEnd();
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glPopMatrix();
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glutSwapBuffers();
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}
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static void Reshape( int width, int height )
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{
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glViewport( 0, 0, width, height );
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}
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static void Key( unsigned char key, int x, int y )
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{
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const GLfloat step = 3.0;
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(void) x;
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(void) y;
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switch (key) {
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case 'a':
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Anim = !Anim;
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if (Anim)
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glutIdleFunc(Idle);
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else
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glutIdleFunc(NULL);
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break;
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case 'z':
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Zrot -= step;
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break;
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case 'Z':
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Zrot += step;
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break;
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case 'b':
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Bias -= 10;
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break;
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case 'B':
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Bias += 10;
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break;
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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case '8':
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case '9':
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Bias = 100.0 * (key - '0');
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break;
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case 27:
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glutDestroyWindow(win);
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exit(0);
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break;
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}
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glutPostRedisplay();
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}
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static void SpecialKey( int key, int x, int y )
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{
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const GLfloat step = 3.0;
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(void) x;
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(void) y;
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switch (key) {
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case GLUT_KEY_UP:
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Xrot -= step;
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break;
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case GLUT_KEY_DOWN:
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Xrot += step;
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break;
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case GLUT_KEY_LEFT:
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Yrot -= step;
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break;
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case GLUT_KEY_RIGHT:
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Yrot += step;
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break;
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}
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glutPostRedisplay();
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}
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static void Init( void )
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{
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GLfloat maxBias;
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if (!glutExtensionSupported("GL_EXT_texture_lod_bias")) {
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printf("Sorry, GL_EXT_texture_lod_bias not supported by this renderer.\n");
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exit(1);
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}
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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if (glutExtensionSupported("GL_SGIS_generate_mipmap")) {
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/* test auto mipmap generation */
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GLint width, height, i;
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GLenum format;
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GLubyte *image = LoadRGBImage(TEXTURE_FILE, &width, &height, &format);
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if (!image) {
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printf("Error: could not load texture image %s\n", TEXTURE_FILE);
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exit(1);
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}
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/* resize to 256 x 256 */
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if (width != 256 || height != 256) {
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GLubyte *newImage = malloc(256 * 256 * 4);
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gluScaleImage(format, width, height, GL_UNSIGNED_BYTE, image,
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256, 256, GL_UNSIGNED_BYTE, newImage);
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free(image);
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image = newImage;
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}
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printf("Using GL_SGIS_generate_mipmap\n");
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glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE);
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glTexImage2D(GL_TEXTURE_2D, 0, format, 256, 256, 0,
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format, GL_UNSIGNED_BYTE, image);
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free(image);
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/* make sure mipmap was really generated correctly */
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width = height = 256;
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for (i = 0; i < 9; i++) {
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GLint w, h;
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glGetTexLevelParameteriv(GL_TEXTURE_2D, i, GL_TEXTURE_WIDTH, &w);
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glGetTexLevelParameteriv(GL_TEXTURE_2D, i, GL_TEXTURE_HEIGHT, &h);
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printf("Level %d size: %d x %d\n", i, w, h);
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assert(w == width);
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assert(h == height);
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width /= 2;
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height /= 2;
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}
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}
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else if (!LoadRGBMipmaps(TEXTURE_FILE, GL_RGB)) {
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printf("Error: could not load texture image %s\n", TEXTURE_FILE);
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exit(1);
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}
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/* mipmapping required for this extension */
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
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glGetFloatv(GL_MAX_TEXTURE_LOD_BIAS_EXT, &maxBias);
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printf("LOD bias range: [%g, %g]\n", -maxBias, maxBias);
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BiasMin = -100 * maxBias;
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BiasMax = 100 * maxBias;
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/* Since we have (about) 8 mipmap levels, no need to bias beyond
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* the range [-1, +8].
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*/
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if (BiasMin < -100)
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BiasMin = -100;
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if (BiasMax > 800)
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BiasMax = 800;
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}
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int main( int argc, char *argv[] )
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{
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glutInit( &argc, argv );
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glutInitWindowPosition( 0, 0 );
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glutInitWindowSize( 350, 350 );
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glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
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win = glutCreateWindow(argv[0]);
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glutReshapeFunc( Reshape );
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glutKeyboardFunc( Key );
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glutSpecialFunc( SpecialKey );
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glutDisplayFunc( Display );
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if (Anim)
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glutIdleFunc(Idle);
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Init();
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glutMainLoop();
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return 0;
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}
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